Generally speaking, a hot water heating installation as shown in accompanying FIG. 1 includes a three-way modulating mixer valve 1 for regulating the departure temperature of water entering a set of radiators 3 from a boiler 2 as a function of the outside temperature.
The valve 1 is controlled by a proportional (P) or a proportional-plus-derivative (PD) type regulator 4 which compares the outside temperature Text with the water departure temperature Td, which it measures at a point 5 located between the valve 1 and the set of radiators, and which generates, in response thereto, two on/off signals on lines 6 and 7 for actuating a motor 8 associated with the valve 1 as a function of said temperatures.
Preferred implementations ofthe present invention serve to improve such a pre-existing installation by adding a plurality of auxiliary heat generators, such as heat pumps, for offloading the main heat generator, while keeping the cost of such a transformation within limits, and in particular while retaining the existing regulator and valve.
More particularly, regulation as provided in accordance with the present invention seeks:
to give priority to operating the auxiliary generators (heat pumps) over the conventional boiler, and to authorize combined operation of the auxiliary generators and the boiler, where it is appropriate for the boiler to make good shortfalls of heat supply when demand exceeds the capabilities of the heat pumps;
to switch the heat pumps on and off with sufficiently long on periods and off periods to ensure optimum operation thereof; and
to control the mixing valve progressively and to switch on the boiler, which is itself controlled by its own thermostat.